Checking the elements of the ISF3.8 charging system

This article covers the inspection of the battery charging system components.

Precautions during inspection

  • Make sure the battery leads are connected to the correct terminals.
  • During boost charging of the battery, disconnect the leads from its terminals.
  • Do not use a high-voltage tester with high input impedance for measurements.
  • Do not disconnect the leads from the battery terminals with the engine running.
  • Disconnect the battery negative terminal first and reconnect it last.

Several types of alternator are used with this engine:

Delco-Remy three-phase alternator

Diagram of the Delco-Remy three-phase alternator
Delco-Remy three-phase alternator: 1, 6 — control lamp; 2 — voltage measurement terminal; 3 — earth terminal; 4 — indicator; 5 — battery terminal.

Delco-Remy single-phase alternator

Diagram of the Delco-Remy single-phase alternator
Delco-Remy single-phase alternator: 3 — earth terminal; 4 — indicator; 5 — battery terminal; 6 — control lamp indicator.

Bosch alternator

Diagram of the Bosch alternator
Bosch alternator: 1 — charge control lamp; 2 — battery positive terminal; 3 — speed indicator; 4 — earth terminals.

The diagrams of the starting and charging systems of vehicles with the ISF3.8 engine are presented in the article — Inspection of the starting system components.

On-vehicle checks

  1. Inspect the battery. If serious damage or electrolyte leakage is found, replace the battery.
  2. Disconnect and check the battery terminals and cables for damage and corrosion. Replace them if necessary.
  3. If corrosion is found on the terminals, clean them to a bright finish with a brush.
    Cleaning the battery terminals with a brush
    Fig. 1. Cleaning the battery terminals.
  4. Check the accessory drive belt for damage and excessive wear and make sure it is correctly seated in the pulley grooves. Replace the belt if necessary.
  5. Check the alternator pulley mounting on the shaft. If it is loose, remove the pulley and check for damage.
  6. If the alternator does not rotate or rotates with difficulty, it must be replaced.

Checking the battery discharge control lamp circuit

  1. Warm the engine up to operating temperature and stop it.
  2. Switch off all auxiliary equipment.
  3. Turn the ignition key to the “ON” position. The battery discharge control lamp must illuminate.
  4. Start the engine. The lamp must go out. If these conditions are not met, continue the check.
    Battery discharge control lamp on the instrument cluster
    Fig. 2. Battery discharge control lamp.

Diagnosing control lamp faults:

  • If the lamp is on when the ignition key is in the “OFF” position and the engine is not running, disconnect the lamp connector from the ignition switch.
    • If the lamp stays on, there is a short to positive in the wiring.
    • If the lamp goes out, there is a short circuit in the ignition switch.
Checking the battery discharge control lamp
Fig. 3. Checking the control lamp.
  • If the lamp does not come on when the ignition key is in the “ON” position and the engine is not running, there is an open circuit.
    • Make sure there is no blown fuse, blown lamp, faulty holder or open circuit between the alternator and the ignition switch.
Checking the control lamp circuit
Fig. 4. Checking the control lamp circuit.
  • If the lamp is on, the ignition key is in the “ON” position and the engine is running, disconnect the lamp terminal from the ignition switch.
    • If the lamp stays on, there is a short to earth in the wiring.
    • If the lamp goes out, check the alternator.
Checking the alternator
Fig. 5. Checking the alternator.
  1. Check the electrolyte level and its density in each battery cell.

Checking the alternator circuits

Check the alternator circuits for open circuits using a tester.

Note: if the tester shows no voltage, there is an open circuit.

Connect the tester to the following terminals and rectify any open circuit:

  • between the alternator battery positive terminal and “earth”;
  • between the alternator “L” flat terminal and “earth”;
  • between the alternator “W” flat terminal and “earth”.
Checking the alternator circuits with a tester
Fig. 6. Checking the alternator circuits.

Checking the alternator voltage and current

  1. Disconnect all battery terminals going to other batteries.
  2. Connect a digital tester and, at 2000 rpm, measure the voltage.
    Measuring the alternator voltage with a digital tester
    Fig. 7. Measuring the alternator voltage.
  3. Keeping the engine at 2000 rpm, adjust the battery tester so that the alternator load corresponds to the maximum rated current.
  4. Measure the current at the alternator output.

If the output current differs from the rated value by more than 10%, the alternator must be repaired or replaced.

Note: the maximum rated current at the alternator output is stamped on the alternator.

Measuring the current at the alternator output
Fig. 8. Measuring the current at the alternator output.
  1. Stop the engine and disconnect the test equipment. Connect the terminals to the battery.

Removal and installation of the alternator

  1. Disconnect the lead from the battery negative terminal.
  2. Remove the accessory drive belt.
  3. Mark all the alternator leads and disconnect them.
  4. Remove the alternator.

Lever-mounted alternator

  1. Unscrew the alternator bracket bolt. Tightening torque: 40 N·m.
  2. Unscrew the mounting bolt, remove the alternator support bracket and the alternator itself. Tightening torque: 24 N·m.
    Lever-mounted alternator
    Fig. 9. Lever-mounted alternator.

Alternator on a support platform

Unscrew the mounting bolts and remove the alternator. Tightening torques:

  • M10 — 36 N·m;
  • M12 — 64 N·m.
Alternator on a support platform
Fig. 10. Alternator on a support platform.

Pivot-mounted alternator

  1. Unscrew the alternator bracket bolt. Tightening torque: 24 N·m.
    Unscrewing the alternator bracket bolt
    Fig. 11. Unscrewing the alternator bracket bolt.
  2. Unscrew the alternator mounting bolt and remove the alternator. Tightening torque: 40 N·m.
    Removal of the pivot-mounted alternator
    Fig. 12. Removal of the alternator.
  3. Unscrew the alternator bracket mounting bolts and remove the alternator bracket. Tightening torque: 45 N·m.
    Removal of the alternator bracket
    Fig. 13. Removal of the alternator bracket.

Installation is carried out in the reverse order of removal.

The above materials cover the inspection of the battery charging system components of the Cummins ISF3.8 engine: precautions, types of alternators used (Delco-Remy three-phase and single-phase, Bosch), on-vehicle checks, checking the battery discharge control lamp circuit, checking the alternator circuits, checking the alternator voltage and current, as well as removal and installation of the alternator. The material is intended for diagnostics, fault-finding and repair of the charging system.